Thermoplastic composites applied to interior materials or parts used in construction, vehicles, filters, etc. may contain polymer powder due to various purposes. For example, the composites may comprise a structure in which the powder is impregnated into fibers. In the case of such a polymer powder, the smaller the particle diameter, the more favorable the subsequent process, and the narrower the particle diameter distribution and the uniform size, the more various applications can be obtained.
Conventionally, spherical fine particles were produced at low cost by using a ball mill grinding method or a freeze grinding method. However, in the freeze grinding method, problems may arise in terms of cost and time since it uses expensive nitrogen to reduce the size of the particles and requires a multi-step grinding process. In addition, since the shape of the final particles produced by the freeze grinding method has a relatively sharp crushed shape, there is a disadvantage in terms of fluidity and various applicability requirements cannot be secured. In the case of the ball mill grinding method, the shape of particles is more spherical than those produced by the freeze grinding method. However, in order to obtain such spherical particles, a separate step of dispersing the particles in a solvent and then recovering them is required. Therefore, this is also disadvantageous in terms of cost and time, and there is a problem in that the particle diameter distribution of the produced particles is wide and uneven, and coagulation occurs easily.
Therefore, there is a need for a method for preparing a spherical powder which is advantageous in terms of cost and time, has little change in physical properties due to temperatures during production, and exhibits excellent physical properties with a narrow particle diameter distribution.